1. Field of the Invention
The invention pertains to television information transmission and reception and more particularly to the transmission and reception of high definition television signals comprising augmentation panels to the left and right of a NTSC compatible center panel, high frequency luminance, and stereo high fidelity audio.
2. Description of the Prior Art
Conventional NTSC color television systems transmit picture information at a rate of 59.94 picture fields per second, two constituting a frame, each frame consisting of 525 horizontal scan lines. To reduce the transmission and reception bandwidths required to reproduce the transmitted picture, these horizontal scan lines are interlaced from field-to-field with a ratio of two-to-one, that is only every other scan line is transmitted in each field. Scan lines omitted in one field are transmitted in the next succeeding field, thus all the odd numbered fields contain one set of scan lines and the even numbered fields contain the set of scan lines which interlace with the scan lines in the odd numbered fields. This arrangement permits the transmission, reception, and picture reproduction at bandwidths reduced from that required for every scan line to be transmitted in each frame.
Television pictures reproduced in these conventional systems have aspect ratio of four to three, i.e. for every four units of horizontal width there are three units of vertical height. High definition television (HDTV) systems may utilize TV screens with aspect ratios that are increased from the conventional 4:3 to aspect ratios of 16:9 and transmit information for an entire image frame without field interlacing, thus providing improved picture resolution. To maintain compatibility with existing TV receivers the wide aspect ratio HDTV source picture is divided into three panels, the center panel comprising the conventional aspect ratio TV picture and the augmentation information for the wide aspect ratio HDTV display at a receiver augmentation for HDTV contained in the panels on the left and right of this center panel. The augmentation signals for providing the left and right panels are transmitted separately from the conventional TV signals. These signals are combined in the HDTV receiver, while the augmentation signals are ignored by the conventional receivers. Additionally, sound quality is improved with the transmission of digital stereo audio of compact disc quality.
Techniques for providing HDTV-NTSC compatible television signals and augmentation signals are disclosed in U.S. patent application Ser. No. 057,847 filed June 2, 1987; Ser. No. 057,849 filed June 2, 1987; Ser. No. 122,148 filed Nov. 17, 1987; and Ser. No. 084,968 filed Aug. 13, 1987. All these applications are assigned to the assignee of the present invention and are incorporated herein by reference.
In addition to the information for extending the picture width, the augmentation signals include information for providing improved resolution by transmitting a line differential signal, and a high frequency luminance component. As previously configured, these transmissions required a channel bandwidth of 6 MHz. It is the purpose of this invention to provide a system that transmits the augmentation information within a 4 MHz channel.